9/11 is a term used to refer to an attack on that date, September 11, 2001. Two airplanes purposefully crashed into the World Trade Center, causing the two towers to crash to the ground. Over 3,000 people were killed in both the planes and in the buildings. Another airplane crashed into the Pentagon killing people in the air and the Pentagon. Another aircraft took over by passengers and crashed in a field, sparing many people’s lives. All of these airplanes had been hijacked by terrorists. To this day, many people remember what happened when people refer to 9/11.